Success!

The airconditioning control unit was installed today. A lot more work than was anticipated by the people involved and at some point I had to go to a DIY store to get a DIN rail and a power cord to make sure everything could be connected as planned.

Of course, this included the cable I prepared to see if I could read data from RS485 modbus interface. Much to my surprise, I received the correct data at the first run of the script I had prepared. I patted myself on the shoulder for that :-).

Now it’s almost midnight and the result of my tinkering is that I am not only able to read the current data from the control unit, but I can change the status and setpoint for each room as well. This bodes well for integrating the whole thing into Home Assistant, which will be a task for another day…